Biological systems, such as healing and embryonic development, operate under spatially- and temporally-controlled orchestration. A myriad of signals and cells all act, in space and time, to heal a cut, for example, or to surround and neutralize a foreign body. The efficacy of current materials used to construct biomedical devices is limited by a lack of multi-functional structures to complement the inherent dynamics of these biological systems.
For example, most wound dressings provide nothing more than a simple barrier to shield the wound and to prevent foreign objects from entering the would. Other newer types of dressings also include antibiotics to prevent sepsis at the wound site. However, these dressings do not address, for example, the exudation which occurs from a wound. Thus, these dressings must be changed often.
Certain biodegradable polymers have been used in burn dressings, hemostatic patches, and the like. These biodegradable polymers provide a barrier and possibly a tissue scaffold for regrowth. However, these types of dressing have no therapeutic effect. While such types of dressings provide effective barriers to physical disturbance of the wound site, scarring is still extensive.
Despite the extensive investigation of novel wound dressing materials, very few materials are in current clinical use. An ideal functional wound dressing should have the following properties: It should be non-toxic, biocompatible, and permeable to moisture and gases to absorb wound exudate and toxins as well to maintain appropriate humidity and oxygen levels. It should be porous to prevent swelling of the wound bed and accumulation of the fluid between the wound site and the material. It should be flexible and durable and minimize local inflammation and infection, thereby promoting new vascularization, re-epithelialization, and normal healing.
Hydrogels are three-dimensional networks capable of absorbing copious amounts of water. Hydrogels have been explored for many uses, including drug delivery devices, wound dressing materials, contact lenses, and cell transplantation matrices. Edible hydrogels, such as gelatin, find extensive use in various food-related applications, such as texture modification, gelling, clarification of beers and wines, and as medicine capsules.